The New Chain Of Rocks Bridge is a pair of bridges across the Mississippi River on the north edge of St. Louis, Missouri. It was constructed in 1966 to bypass the Chain of Rocks Bridge immediately to the south. It originally carried traffic for Bypass US 66 and currently carries traffic for Interstate 270. The bridge opened to traffic on September 2, 1966.
The original Chain of Rocks Bridge was a narrow bridge with a 22 degree bend midway over the river. Reportedly, two tractor-trailers could not pass each other on that bridge. The Illinois Department of Transportation (IDOT) marks Historic Route 66 over the New Chain of Rocks Bridge (with a "Spur historic route" to the original), but it is only considered a way to make the route continuous.